1. Field of the Invention
The present invention relates to a lens interchangeable image-pickup apparatus, such as a video camera.
2. Description of the Related Art
In a lens interchangeable type camera system, an image-pickup apparatus, such as a video camera, generates a focus signal, and an interchangeable lens attachable to the image-pickup apparatus drives a focus lens. It is necessary to properly manage generating timing of the focus signal and driving timing of the focus lens. For example, Japanese Patent Laid-Open No. (“JP”) 2009-258718 discloses a method for wobbling in the contrast AF (“TVAF”) control in the lens interchangeable type camera system in which a camera controller sets the driving timing of the focus lens and transmits the set driving timing to a lens controller.
In a proposed AF system for a lens interchangeable type camera in which a focus sensitivity of an attached lens is unknown, a camera microcomputer provides the AF control and transmits a driving command of a focus lens to a lens microcomputer. For wobbling and mountain-climbing of the TVAF control in this AF system, the lens microcomputer needs to correctly recognize the current AF operation mode in the camera. The lens microcomputer also needs to correctly control driving of the focus lens in accordance with the AF operation mode of the camera so as to prevent the malfunction.
Information that the lens microcomputer needs for the mountain-climbing may be different from that for the wobbling. Therefore, when the method disclosed in JP 2009-258718 for the wobbling is applied to the mountain-climbing, the lens microcomputer may not properly control driving of the focus lens in the mountain-climbing. As a solution for this problem, it is conceivable to change a communication mode in the mountain-climbing and to transmit necessary information from the camera microcomputer to the lens microcomputer. Nevertheless, the system becomes complex, because if the operation is frequently switched between the wobbling and the mountain-climbing, the communication mode is also frequently switched.